Burner and coal upgrading plant

ABSTRACT

Provided is a burner that includes: a tubular first outer cylinder ( 20 ); a diffuser ( 21 ) disposed inside the first outer cylinder ( 20 ) and having an inner circumferential surface, a diameter of which gradually increases in a first direction; a first gas nozzle ( 22 ) configured to feed a first gas to a radial outer region of the diffuser ( 21 ) in the first direction; a second gas nozzle ( 23 ) disposed adjacent to the first gas nozzle ( 22 ) in a circumferential direction of the first outer cylinder ( 20 ) and configured to feed a second gas to the radial outer region of the diffuser ( 21 ) in the first direction; and an ignition torch ( 24 ) configured to ignite at least one of the second gas and the first gas.

TECHNICAL FIELD

The present invention relates to a burner and a coal upgrading plant.

Priority is claimed on Japanese Patent Applications No. 2013-199699, filed on Sep. 26, 2013, the contents of which are incorporated herein by reference.

BACKGROUND ART

In coal upgrading plants that upgrade low-grade coal to high-grade coal, pyrolytic treatment is performed in some cases to remove impurities such as mercury contained in the low-grade coal. When this pyrolytic treatment is performed, a combustible gas is separated from the low-grade coal. In some cases, this combustible gas is burnt in a combustion furnace and is reused as a high-temperature gas. This high-temperature gas is sent to a jacket such as a rotary kiln as, for instance, a heat source for pyrolyzing the low-grade coal, and then is discharged to the outside via, for instance, an exhaust gas purifier.

The combustible gas obtained from the low-grade coal is generally a low-calorie gas. For this reason, if the combustible gas cannot be stably burnt due to lack of a calorific value when burnt in the combustion furnace, a high-calorie gas such as natural gas is partly input into the combustion furnace, and the low-grade coal and the high-calorie gas are sometimes burnt at the same time. In the above coal upgrading plant, a burner for the high-calorie gas which is an auxiliary burner is disposed in the vicinity of a burner for the low-calorie gas in order to improve transfer of flames from the high-calorie gas to the low-calorie gas. Further, an ignition torch is disposed in the vicinity of the burner for the high-calorie gas.

However, since it is necessary to individually feed air to each of the burners, for instance, the burner for the low-calorie gas and the burner for the high-calorie gas, pipes are complicated. Further, since each of the burners is individually mounted on a wall surface of the combustion furnace via dedicated pipe stands, the number of pipe stands is increased and it is hard to reduce the size of the plant.

A combustor equipped with a nozzle for a low-calorie gas and a nozzle for a high-calorie gas is set forth in Patent Literature 1. The nozzle for the low-calorie gas feeds the low-calorie gas. The nozzle for the high-calorie gas feeds the high-calorie gas to an inner center of the nozzle for the low-calorie gas. This combustor burns the low-calorie gas and the high-calorie gas at the same time.

A mixed combustion type burner that burns a high-calorie fuel such as natural gas using an auxiliary burner to assist with combustion of an exhaust gas using flames of the high-calorie fuel is set forth in Patent Literature 2.

CITATION LIST Patent Literature [Patent Literature 1]

U.S. Pat. No. 8,220,272

[Patent Literature 2]

U.S. Pat. No. 4,154,567

SUMMARY OF INVENTION Problem to be Solved by the Invention

Meanwhile, in the coal upgrading plant, the high-calorie gas is ignited for the purpose of raising a temperature during plant start-up. However, an inert gas (e.g., nitrogen) is used to purge the kiln that pyrolyzes the low-grade coal during the plant start-up. In that case, the inert gas is sometimes fed in the vicinity of the nozzle for the high-calorie gas via the nozzle for the low-calorie gas. As a result, flames of the nozzle for the high-calorie gas disposed in the vicinity of the nozzle for the low-calorie gas are accidentally misfired in some cases.

An object of the present invention is to provide a burner and a coal upgrading plant that are capable of reducing accidental misfire of flames of a high-calorie gas due to an inert gas ejected from a nozzle for a low-calorie gas when a nozzle for the high-calorie gas is disposed in the vicinity of the nozzle for the low-calorie gas.

Means for Solving the Problem

According to a first aspect of the present invention, a burner is a burner that simultaneously burns a first gas and a second gas having a higher calorific value than the first gas. This burner includes: a tubular first outer cylinder having an opening through which primary air is fed in a first direction; and a diffuser disposed inside the first outer cylinder and having an inner circumferential surface, a diameter of which gradually increases in the first direction. This burner further includes: a first gas nozzle disposed inside the first outer cylinder and configured to feed the first gas to a radial outer region of the diffuser in the first direction; and a second gas nozzle disposed adjacent to the first gas nozzle in a circumferential direction of the first outer cylinder and configured to feed the second gas to the radial outer region of the diffuser in the first direction. This burner further includes an ignition torch disposed inside the first outer cylinder and configured to ignite at least one of the second gas and the first gas.

According to a second aspect of the present invention, in the burner of the first aspect, an opening end of the first gas nozzle in the first direction may include a contact portion configured to abut along an outermost circumferential portion of the diffuser.

According to a third aspect of the present invention, the burner of the second aspect may include a plurality of first gas nozzles, and a sum of circumferential angle ranges within which the each contact portion of the first gas nozzles come into contact with the diffuser may range from 90 degrees to 200 degrees.

According to a fourth aspect of the present invention, in the burner of any one of the first to third aspects, the second gas nozzle may include a flame holding pad that generates a vortex of the second gas at an opening end thereof in the first direction.

According to a fifth aspect of the present invention, the burner of any one of the first to fourth aspects may include a second outer cylinder disposed outside the first outer cylinder and configured to form a flow channel through which secondary air flows between the first outer cylinder and the second outer cylinder.

According to a sixth aspect of the present invention, the burner of the fifth aspect may include swirlers disposed between the first outer cylinder and the second outer cylinder and configured to swirl the second air in a circumferential direction.

According to a seventh aspect of the present invention, the burner of any one of the first to sixth aspects may include a temperature drop reducing part configured to cover at least a part of an outer circumferential surface of the first gas nozzle and to prevent a drop in temperature of the first gas.

According to an eighth aspect of the present invention, a coal upgrading plant includes a combustion furnace provided with the burner according to any one of the first to seventh aspects.

Effects of the Invention

According to the burner and the coal upgrading plant, it is possible to reduce accidental misfire of flames of a high-calorie gas due to an inert gas ejected from a nozzle for a low-calorie gas when a nozzle for the high-calorie gas is disposed in the vicinity of the nozzle for the low-calorie gas.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic constitutional view of a coal upgrading plant (1) in this embodiment.

FIG. 2 is a sectional view illustrating a schematic constitution around a burner of a combustion furnace of this invention.

FIG. 3 is a front view of the burner (10) when viewed in a direction III of FIG. 2.

FIG. 4 is a sectional view taken along line VI-VI of FIG. 3.

FIG. 5 is a perspective view illustrating a state in which a temperature drop reducing part is mounted on a first gas nozzle of the burner.

FIG. 6 is a map illustrating primary air ratios at which stable combustion is possible with respect to an input heat rate (%) of a second gas nozzle (23).

FIG. 7 is a map illustrating primary air mixed oxygen concentrations (vol %) at which stable combustion is possible with respect to a primary air ratio.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a coal upgrading plant according to an embodiment of the present invention will be described.

FIG. 1 is a schematic constitutional view of the coal upgrading plant 1 in this embodiment.

The coal upgrading plant 1 in this embodiment is a plant that removes moisture, impurities, etc. contained in low-grade coal to mold the low-grade coal, and thereby converts the low-grade coal to high-grade coal.

As illustrated in FIG. 1, the coal upgrading plant 1 is mainly equipped with a crusher 2, a drier 3, a pyrolyzer 4, a combustion furnace 5, a quencher 6, a finisher 7, a kneader 8, and a briquetting device 9.

The crusher 2 crushes raw coal L, and thereby adjusts a size of the raw coal L to a size at which the raw coal L is easily processed in a subsequent process. The raw coal L, the size of which is adjusted by the crusher 2, is sent to the drier 3.

The drier 3 dries the raw coal L, the size of which is adjusted by the crusher 2. As this drier 3, for example, a steam tube drier indirectly heating the raw coal L using steam may be used. The coal dried by the drier 3 is sent to the pyrolyzer 4.

The pyrolyzer 4 is a device that slightly pyrolyzes the coal dried by the drier 3. To be more specific, the pyrolyzer 4 gasifies and extracts volatile components and various impurities such as mercury contained in the coal. A gas separated by this pyrolyzer 4 is sent to the combustion furnace 5 as a low-calorie gas (first gas). The upgraded coal that has been pyrolyzed by the pyrolyzer 4 is sent to the quencher 6.

The combustion furnace 5 burns the low-calorie gas separated by the pyrolyzer 4 along with, for instance, primary air to generate a high-temperature gas. This high-temperature gas is fed to a jacket 4 a of the pyrolyzer 4, and is used as a heat source of the pyrolyzer 4. The high-temperature gas used to heat the raw coal L by this pyrolyzer 4 is purged by, for instance, an exhaust clean system (AQCS) Cs, and then is discharged to the atmosphere. In FIG. 1, a reference sign “F” indicates an air volume adjusting fan, and a reference sign “B” indicates a blower. The air volume adjusting fan F and the blower B, which are installed on a pipe between the jacket 4 a and the exhaust clean system Cs, deliver the spent high-temperature gas to the exhaust clean system Cs together.

The quencher 6 cools the upgraded coal that has been subjected to the pyrolytic treatment by the pyrolyzer 4. A temperature of the upgraded coal which was about 400° C. is cooled to 70° C. or so by this quencher 6. The upgraded coal cooled by the quencher 6 is sent to the finisher 7.

The finisher 7 moderately adjusts the temperature of the upgraded coal that is cooled to some extent by the quencher 6 using, for instance, the atmosphere again. The finisher 7 adjusts the temperature of the upgraded coal, for instance, to be equal to or less than 50° C. The upgraded coal, the temperature of which is adjusted by the finisher 7, is sent to the kneader 8.

The kneader 8 pulverizes the upgraded coal, the temperature of which is adjusted by the finisher 7, and forms it into a finer particle shape. When an additive such as a binder for molding the upgraded coal along with the pulverization is needed, the kneader 8 inputs the binder into the upgraded coal, and agitates the upgraded coal. The upgraded coal pulverized and agitated by the kneader 8 is sent to the briquetting device 9.

The briquetting device 9 molds the upgraded coal into a predetermined briquette shape. The briquetting device 9 molds the upgraded coal into the briquette shape by, for instance, compression molding. Briquettes Br of the upgraded coal molded by this briquetting device 9 are transported to a destination by a transporting means such as a vehicle, a ship, or the like.

Next, a burner 10 of the aforementioned combustion furnace 5 will be described on the basis of the drawings.

FIG. 2 is a sectional view illustrating a schematic constitution around the burner 10 of the combustion furnace 5.

As illustrated in FIG. 2, the combustion furnace 5 is equipped with a container 11 that forms a space K for combustion. The burner 10 is mounted in this container 11 via one pipe stand 11 a. The burner 10 burns two types of gases having different calorific values. An end 10 a of the burner 10 which is adjacent to the space K has the same position as an inner surface 11 b of the container 11 in a direction of an axis O of the burner 10. Pipes 12 a to 12 d for feeding a low-calorie fuel, a high-calorie fuel, an ignition torch fuel, and air are connected to the burner 10. Flow regulating valves 13 a to 13 d are mounted on the respective pipes 12 a to 12 d. In an example of this embodiment, the low-calorie gas that is generated by the pyrolyzer 4 and acts as the low-calorie fuel is fed to the burner 10. Further, in an example of this embodiment, a high-calorie gas (second gas) such as natural gas that has a higher calorific value than the low-calorie gas and acts as the high-calorie fuel is fed to the burner 10. The air fed to the burner 10 is used as primary and secondary air to be described below.

FIG. 3 is a front view of the burner 10 when viewed in a direction III of FIG. 2. FIG. 4 is a sectional view taken along line VI-VI of FIG. 3.

As illustrated in FIGS. 3 and 4, the burner 10 is equipped with a first outer cylinder 20, a diffuser 21, first gas nozzles 22, second gas nozzles 23, ignition torches 24, and a second outer cylinder 25.

The first outer cylinder 20 forms a flow channel that feeds the primary air toward the internal space K. The first outer cylinder 20 is formed in a tubular shape, and more particularly in a cylindrical shape. The first outer cylinder 20 has an opening 27 at a side of the internal space K (hereinafter referred to simply as “first direction”) in a direction of an axis O thereof.

The diffuser 21 has an inner circumferential surface 28 that is disposed inside the first outer cylinder 20 and is gradually increased in diameter in the first direction. A conical space is radially formed inside this diffuser 21. When viewed from the side of the internal space K, the diffuser 21 is formed in a circular shape having the same center as the first outer cylinder 20. A position of an outermost circumferential portion 29 that is a first-direction end of the diffuser 21 is disposed at the same position as a first-direction end 30 of the first outer cylinder 20 in the direction of the axis O. Here, an angle θ0 between the inner circumferential surface 28 of the diffuser 21 and the axis O is preferably set to 50 to 70 degrees.

The first gas nozzles 22 are disposed radially inside the first outer cylinder 20. The first gas nozzles 22 feed the low-calorie gas to a radial outer region of the diffuser 21 in the first direction. The burner 10 in this embodiment is provided with a plurality of first gas nozzles 22, and more particularly two first gas nozzles 22. Openings 31 of the first gas nozzles 22 are disposed across the axis O at symmetrical positions.

Opening ends 32 of the first gas nozzles 22 in the first direction have contact portions 33 coming into contact with the diffuser 21. The contact portions 33 are formed along the outermost circumferential portion 29 in a sectional circular arc shape. Each contact portion 33 is in contact with the outermost circumferential portion 29 of the diffuser 21 over an entire circumferential region thereof. Thereby, the primary air flowing inside the first outer cylinder 20 is configured not to flow between the contact portions 33 of the first gas nozzles 22 and the outermost circumferential portion 29 of the diffuser 21 in the first direction. If circumferential angle ranges within which the two contact portions 33 come into contact with the outermost circumferential portion 29 of the diffuser 21 are set to θ1 and θ2, the sum of these angle ranges θ1 and θ2 ranges from 90 degrees to 200 degrees.

The opening end 32 of each of the first gas nozzles 22 is provided with two sidewall portions 34 that extend in parallel from circumferential opposite sides of the contact portion 33 toward the first outer cylinder 20. The opening end 32 is provided with an outer wall portion 34 a that connects ends of the parallel sidewall portions 34 which are adjacent to the first outer cylinder 20. The outer wall portion 34 a is formed in a sectional circular arc shape in which it protrudes toward the first outer cylinder 20 to extend along the inner surface of the first outer cylinder 20.

The second gas nozzles 23 feed the high-calorie gas to the radial outer region of the diffuser 21 in the first direction. The burner 10 in this embodiment is provided with a plurality of second gas nozzles 23, and more particularly two second gas nozzles 23. The second gas nozzles 23 are disposed adjacent to the first gas nozzles 22 in the circumferential direction of the first outer cylinder 20. Further, the two second gas nozzles 23 are disposed across the axis O at symmetrical positions.

Opening ends 35 of the second gas nozzles 23 in the first direction are disposed upstream from the outermost circumferential portion 29 of the diffuser 21 in the first direction. That is, when viewed from the side of the internal space K, the opening ends 35 of the second gas nozzle 23 are disposed behind the diffuser 21. A distance d between the outermost circumferential portion 29 of the diffuser 21 and the opening end 35 of each of the second gas nozzles 23 in the direction of the axis O may be set to 0 to 30 mm. Also, the distance d is more preferably set to 0 mm.

The opening end 35 of each of the second gas nozzles 23 is provided with a flame holding pad 36. When the high-calorie gas fed from each of the second gas nozzles 23 is ignited, the flame holding pad 36 functions to hold flames of the high-calorie gas. To be specific, each of the flame holding pads 36 has a plane 37 that extends in a direction perpendicular to the first direction to block the opening end 35 in the first direction. The flame holding pad 36 has a plurality of through-holes 38, each of which has a smaller cross section than the flow channel of the second gas nozzle 23 at the opening end 35. These through-holes 38 communicate between the internal space of the second gas nozzle 23 and the radial outer region of the outermost circumferential portion 29 of the diffuser 21. When the high-calorie gas flowing through the second gas nozzle 23 goes through the through-holes 38 to run out of the second gas nozzle 23, a small vortex (not illustrated) is formed around the through-holes 38. Accidental misfire of the flames of the high-calorie gas is reduced by this small vortex.

Here, the flame holding pads 36 in this embodiment can efficiently hold the flames when widths w directed from the second gas nozzles 23 toward the diffuser 21 are set to 5 to 20 mm in order to hold the flames of the second gas nozzles 23. Further, each of the widths w is more preferably set to 10 mm. That is, the primary air sometimes flows between the flame holding pads 36 and the diffuser 21.

The ignition torches 24 form a source that ignites at least one of the aforementioned high- and low-calorie gases. The aforementioned ignition torch fuel is fed to the ignition torches 24. The ignition torches 24 are disposed between the first gas nozzles 22 and the second gas nozzles 23 inside the first outer cylinder 20. In this embodiment, an example in which the two ignition torches 24 are provided is given, but one ignition torch 24 may be provided.

The second outer cylinder 25 forms a flow channel through which secondary air flows between the first outer cylinder 20 and the second outer cylinder 25. The second outer cylinder 25 is disposed to cover the outside of the first outer cylinder 20 at a predetermined interval. The second outer cylinder 25 overlaps the first outer cylinder 20 at the axis O, and is formed in a cylindrical shape having a larger diameter than the first outer cylinder 20. That is, the flow channel through which the secondary air flows is formed such that a radial dimension thereof is the same throughout the circumference of the first outer cylinder 20.

A plurality of swirlers 39 are disposed between the first outer cylinder 20 and the second outer cylinder 25. These swirlers 39 are disposed at predetermined regular intervals in a circumferential direction. The swirlers 39 function as deflection plates that swirl the secondary air around the axis O. That is, a flow of the secondary air that flows from the flow channel between the first outer cylinder 20 and the second outer cylinder 25 to the internal space K becomes a swirl flow having a cylindrical shape and a spiral shape. Due to this swirl flow of the secondary air, a region adjacent to the opening 27 at a radial inner side thereof becomes a negative pressure. Thus, due to this negative pressure, as the secondary air is separated from the opening 27 in the direction of the axis O, its diameter is gradually reduced. Thereby, since the primary air, the low-calorie gas, and the high-calorie gas that flow out to the inside of the secondary air are collected toward the axis O, the accidental misfire of the flames can be further reduced. Here, a blade angle for swirling the secondary air is set to 0 to 45 degrees, and thereby the swirlers 39 in this embodiment can effectively reduce the accidental misfire of the flames. Further, the blade angle is more preferably set to 30 degrees.

FIG. 5 is a perspective view illustrating a state in which a temperature drop reducing part 40 is mounted on the first gas nozzle 22.

As illustrated in FIG. 5, the burner 10 is equipped with the temperature drop reducing part 40 that reduces a drop in temperature of the first gas nozzle 22. This temperature drop reducing part 40 covers at least a part of an outer circumferential surface 41 of the first gas nozzle 22. The temperature drop reducing part 40 is provided with at least one of a heater that can heat the first gas nozzle 22 and an insulator that can insulate the first gas nozzle 22. Thereby, it is possible to reduce a drop to a temperature that is equal to or lower than a condensation temperature of tar, etc. contained in the high-temperature low-calorie gas sent from the pyrolyzer 4, and the resultant condensation.

The burner 10 in this embodiment has the aforementioned constitution.

FIG. 6 is a map illustrating primary air ratios at which stable combustion, i.e., stabilized ignition and stabilized flame retention, is possible with respect to an input heat rate (%) of the second gas nozzle 23. Here, the primary air ratio is defined as a theoretical air quantity ratio between a total flow rate of the primary air and a total flow rate of the high-calorie gas. Also, the input heat rate of the second gas nozzle 23 is a value indicating how much of the high-calorie gas is contained in a total flow rate of the low- and high-calorie gases, and is defined as “the input heat of the high-calorie gas/(the input heat of the low-calorie gas+the input heat of the high-calorie gas)×100 (%).”

The burner 10 is adjusted according to the input heat rate of the second gas nozzle 23 to have the primary air ratio greater than a lower limit indicated by a solid line of FIG. 6. In FIG. 6, “o” indicates the primary air ratio at which the stable combustion (including the stable ignition and the stable flame retention) was verified by a test, over the input heat rate of the second gas nozzle 23. Also, in FIG. 6, “x” indicates the primary air ratio at which unstable combustion was verified by a test, over the input heat rate of the second gas nozzle 23.

As illustrated in FIG. 6, as the input heat rate of the second gas nozzle 23 decreases, a rising rate of the lower limit the primary air ratio drastically increases, and it is difficult to carry out flow rate adjustment as well as stable combustion of the primary air. For this reason, the flow rate of the high-calorie gas is preferably adjusted such that the input heat rate is greater than 10%. However, from the viewpoint of energy saving, the flow rate of the high-calorie gas is adjusted to be as small as possible.

FIG. 7 is a map illustrating primary air mixed oxygen concentrations (vol %) at which stable combustion, i.e., stabilized ignition and stabilized flame retention, is possible with respect to a primary air ratio. Here, the primary air mixed oxygen concentration is a value indicating how much oxygen in primary air is contained in a total flow rate of the primary air and an inert gas (e.g., nitrogen), and is defined as “the flow rate of the oxygen deposited in the primary air/(the flow rate of the primary air+the flow rate of the inert gas)×100 (%).”

When the inert gas is used to purge the pyrolyzer 4, the inert gas flows out of the first gas nozzles 22. In this case, the burner 10 is set to have a primary air mixed oxygen concentration that is greater than a lower limit indicated by a solid line of FIG. 7 according to a primary air ratio, and thereby stable combustion, i.e., stabilized ignition and stabilized flame retention, is possible. In FIG. 7, “o” indicates the primary air mixed oxygen concentration at which the stable combustion (including the stable ignition and the stable flame retention) was verified by a test, over the primary air ratio. Also, in FIG. 4, “x” indicates the primary air mixed oxygen concentration at which unstable combustion was verified by a test, over the primary air ratio.

As illustrated in FIG. 7, the lower limit of the primary air mixed oxygen concentration is lowest when the primary air ratio is about “2.” Thus, as the primary air ratio increases from a value at which the primary air mixed oxygen concentration is lowest, the lower limit of the primary air mixed oxygen concentration smoothly increases. On the other hand, as the primary air ratio decreases from the value at which the primary air mixed oxygen concentration is lowest, the lower limit of the primary air mixed oxygen concentration drastically increases. For this reason, the flow rate of the primary air is preferably adjusted such that the primary air ratio is greater than “1.”

The adjustment of the primary air ratio and the adjustment of the primary air mixed oxygen concentration may be designed to be automatically performed by executing a pre-stored program on a computer.

When the primary air ratio and the primary air mixed oxygen concentration are automatically adjusted, for example, actuators (not illustrated) that individually drive the flow regulating valves 13 a to 13 c and flow meters (not illustrated) that measure the flow rate of the high-calorie gas, the flow rate of the low-calorie gas, and the flow rate of the primary air are provided. The computer calculates the input heat rate of the second gas nozzle 23 on the basis of a measured result of each of the flow meters, and finds the primary air ratio and the primary air mixed oxygen concentration at which the stable combustion is obtained with reference to the map. Further, the computer controls the flow rate of the primary air to have the found primary air ratio. Here, the adjustment of the primary air ratio is not limited to automatically controlling it. Instead of the control process based on the computer, for example, the measured results of the flow meters and the maps illustrated in FIGS. 6 and 7 may be displayed by a display, and thereby a worker may appropriately perform the control of the flow rates.

Therefore, according to the burner 10 of the above embodiment, as illustrated in FIG. 4, the primary air flowing outside the diffuser 21 in the first direction is suctioned to form a swirl at an inner circumferential surface side of the diffuser 21. Further, the high-calorie gas fed from the second gas nozzles 23 is suctioned to this swirl, and thereby a small ball of fire can be produced in the diffuser 21. For this reason, it is possible to ensure mixing the primary air and the high-calorie gas to reduce an influence of the inert gas fed from the first gas nozzles 22. Also, when the low-calorie gas is fed from the first gas nozzles 22, it is possible to suction the low-calorie gas to the diffuser 21 and reliably bum the low-calorie gas.

As a result, when the nozzle for the high-calorie gas is disposed in the vicinity of the nozzle for the low-calorie gas, the accidental misfire of the flames of the high-calorie gas by the inert gas ejected from the nozzle for the low-calorie gas can be reduced.

Also, as the opening ends 32 of the first gas nozzle 22 have the contact portions 33, the low-calorie gas fed from the first gas nozzles 22 can be smoothly suctioned to the diffuser 21 via the contact portions 33.

Further, as the sum of the circumferential angle ranges within which the contact portions 33 come into contact with the diffuser 21 is set to 90 to 200 degrees, a range within which the low-calorie gas is drawn into the diffuser 21 can be set to an optimal range for the combustion of the low-calorie gas.

On the other hand, when the sum of the circumferential angle ranges within which the contact portions 33 come into contact with the diffuser 21 falls below 90 degrees, there is a possibility of the low-calorie gas being unable to be properly fed into the diffuser 21 and to be subjected to the stable combustion. Also, when the sum of the circumferential angle ranges within which the contact portions 33 come into contact with the diffuser 21 falls above 200 degrees, there is a possibility of the range within which the low-calorie gas is drawn into the diffuser 21 being excessively widened, and the high-calorie gas and the primary air being inhibited from being suctioned to the diffuser 21.

Further, when the opening ends 35 of the second gas nozzles 23 in the first direction are disposed upstream from the outermost circumferential portion 29 of the diffuser 21 in the direction of the axis O, even if the inert gas is ejected from the first gas nozzles 22, the inert gas does not flow toward the opening ends 35 of the second gas nozzles 23 disposed upstream from the opening ends 32 of the first gas nozzles 22. For this reason, the accidental misfire of the flames of the second gas nozzles 23 can be reduced by the inert gas.

Also, as the flame holding pads 36 are provided, the vortex caused by the high-calorie gas can be formed around the opening ends 35 of the second gas nozzles 23. For this reason, by igniting the vortex, the flames generated at the second gas nozzles 23 are held, and the accidental misfire of the flames inside the diffuser 21 can be further reduced.

Further, as the second outer cylinder 25 is provided, a downstream space of the first outer cylinder 20 can be surrounded from the outside by the secondary air. For this reason, the primary air, the low-calorie gas, and the high-calorie gas can be more reliably introduced into the diffuser in a greater quantity.

Also, as the swirlers 39 are provided, the space inside the secondary air has the negative pressure due to the swirl of the secondary air, and thus the primary air, the low-calorie gas, and the high-calorie gas can be efficiently introduced into the diffuser 21.

Also, according to the coal upgrading plant 1 in the above embodiment, since the accidental misfire of the flames of the burner 10 can be reduced, the pyrolytic treatment can be stably performed in a coal upgrading process.

The present invention is not limited to the aforementioned embodiment, and includes various upgrades of the aforementioned embodiment without departing from the spirit and scope of the present invention. That is, the specific shapes and constitutions represented in the embodiment are merely examples and can be appropriately upgraded.

For example, in the aforementioned embodiment, the example in which the two first gas nozzles 22, the two second gas nozzles 23, and the two ignition torches 24 are provided has been described. However, the number of first gas nozzles 22, the number of second gas nozzles 23, and the number of ignition torches 24 may be one or more.

Further, the example in which the internal space of the diffuser 21 of the aforementioned embodiment is formed in the conical shape has been described. However, a mounting through-hole passing through the diffuser in the direction of the axis O and a slit extending in a radial direction when viewed from the side of the space K in order to prevent cracks caused by thermal deformation may be provided in the diffuser 21.

Also, in the aforementioned embodiment, the burner 10 provided for the combustion furnace 5 of the coal upgrading plant 1 has been described by way of example, but it may be applied to combustion furnaces other than the coal upgrading plant 1.

INDUSTRIAL APPLICABILITY

The present invention relates to the burner in which the nozzle for the high-calorie gas is disposed in the vicinity of the nozzle for the low-calorie gas, and the coal upgrading plant equipped with this burner. According to the burner and the coal upgrading plant of the present invention, the accidental misfire of the flames of the high-calorie gas by the inert gas ejected from the nozzle for the low-calorie gas can be reduced.

REFERENCE SIGNS LIST

1 Coal upgrading plant

2 Crusher

3 Drier

4 Pyrolyzer

4 a Jacket

5 Combustion furnace

6 Quencher

7 Finisher

8 Kneader

9 Briquetting device

10 Burner

10 a End

11 Container

11 a Pipe stand

11 b Inner surface

12 a to 12 d Pipe

13 a to 13 d Flow regulating valve

20 First outer cylinder

21 Diffuser

22 First gas nozzle

23 Second gas nozzle

24 Ignition torch

25 Second outer cylinder

26 Flow channel

27 Opening

28 Inner circumferential surface

29 Outermost circumferential portion

30 End

31 Opening

32 Opening end

33 Contact portion

34 Wall portion

34 a Outer sidewall portion

35 Opening end

36 Flame holding pad

37 Plane

38 Through-hole

39 Swirler

40 Temperature drop reducing part

41 Outer circumferential surface

B Blower

Br Briquette

Cs exhaust clean system

F Air volume adjusting fan

K Space

L Raw coal 

1. A burner that simultaneously burns a first gas and a second gas having a higher calorific value than the first gas, the burner comprising: a tubular first outer cylinder having an opening through which primary air is fed in a first direction; a diffuser disposed inside the first outer cylinder and having an inner circumferential surface, a diameter of which gradually increases in the first direction; a first gas nozzle disposed inside the first outer cylinder and configured to feed the first gas to a radial outer region of the diffuser in the first direction; a second gas nozzle disposed adjacent to the first gas nozzle in a circumferential direction of the first outer cylinder and configured to feed the second gas to the radial outer region of the diffuser in the first direction; and an ignition torch disposed inside the first outer cylinder and configured to ignite at least one of the second gas and the first gas.
 2. The burner according to claim 1, wherein an opening end of the first gas nozzle in the first direction includes a contact portion configured to abut along an outermost circumferential portion of the diffuser.
 3. The burner according to claim 2, wherein: the burner includes a plurality of first gas nozzles; and a sum of circumferential angle ranges within which each contact portion of the first gas nozzles come into contact with the diffuser ranges from 90 degrees to 200 degrees.
 4. The burner according to claim 1, wherein the second gas nozzle includes a flame holding pad that generates a vortex of the second gas at an opening end thereof in the first direction.
 5. The burner according to claim 1, further comprising a second outer cylinder disposed outside the first outer cylinder and configured to form a flow channel through which secondary air flows between the first outer cylinder and the second outer cylinder.
 6. The burner according to claim 5, further comprising swirlers disposed between the first outer cylinder and the second outer cylinder and configured to swirl the second air in a circumferential direction.
 7. The burner according to claim 1, further comprising a temperature drop reducing part configured to cover at least a part of an outer circumferential surface of the first gas nozzle and to prevent a drop in temperature of the first gas.
 8. A coal upgrading plant comprising a combustion furnace provided with the burner according to claim
 1. 